The people of Houston, Texas were greeted with one of the most impressive UFO sightings ever last week after hundreds of people caught a glimpse of a circle of lights floating above the city.

The unexplained set of lights were caught on August 11 during a thunderstorm and showed a circle of lights surrounding what appeared to be a central beam.

While pictures via Twitter originally showed the lights to be a static object, video footage was then released and showed that actually the lights were completely independent of each other; moving in and out of formation.

WTSP spoke to Dr. Carolyn Sumners, vice president for Astronomy at the Houston Museum of Natural Science, who said, sensibly:

"I think the trick in UFO's is figuring out what else they could be... It's easy to say that could be the aliens."

Usually with mass sightings there is an explanation that follows a few days afterwards -- whether it's a government weather balloon, or an experimental test aircraft. But in this instance there has been no such revelation.

Instead Houston citizens and UFO fans have been left pondering with theories ranging from a drone to other suggesting that actually they were just stadium lights.

For those hoping to have some form of resolution to the mystery prepare to be disappointed as it appears as though both those theories have been discredited, leaving the floating lights as unexplained.

That said, this image which turned up on Twitter is pretty convincing..